Choosing whether you use `{ ... }` or `do ... end` around your blocks is more than just a stylistic choice in Ruby. It also affects the way that an operation will be executed because your choice also specifies the *Operation Precedence* to use. In a nutshell, _a block curly braces has higher precedence than a block with do/end._
Consider this example from a [great Stackoverflow post](http://stackoverflow.com/a/5587399/814576):
```ruby
f param { do_something() }
```
will execute differently than
```ruby
f param do do_something() end
```
The former will bind the block to `param`, while the latter will bind the block to `f`. The more you know...